This invention relates in general to universal joint assemblies for vehicular drive train systems. In particular, this invention relates to a locking cover for protectively covering a lubrication fitting mounted on a cross of a universal joint assembly.
Universal joint assemblies are well known devices that provide a driving connection between two members adapted to rotate about non-aligned axes of rotation. Universal joint assemblies are widely used between rotatable drive shaft sections in vehicle drive train systems. A typical universal joint assembly includes a cross having a central body portion with four cylindrical trunnions extending outwardly from the cross. The trunnions are oriented in a single plane and extend at right angles relative to one another, and the trunnions have a common intersection at the center of the central body portion. A hollow cylindrical bearing cup is mounted on the end of each of the trunnions. Needle bearings or similar means are provided between the outer cylindrical surfaces of the trunnions and the inner cylindrical surfaces of the bearing cups to permit relative rotational movement between the trunnions and the bearing cups. The bearing cups that are mounted on an opposed pair of the trunnions can be connected to a first end yoke secured to an end of a first drive shaft section, while the bearing cups that are mounted on a second opposed pair of the trunnions can be connected to a second end yoke secured to an end of a second drive shaft section.
It is usually necessary to periodically provide lubrication for the bearings between the bearing cups and the trunnions in a universal joint assembly. To accomplish this, the central body portion of the cross has a cavity formed therein that communicates with respective lubricant passageways formed through each of the trunnions. A lubrication fitting is mounted in an aperture formed through the central body portion of the cross. The lubrication fitting is a check valve that allows lubricant to be injected under pressure into the cavity, while preventing such lubricant from leaking outwardly therefrom. During this injection, the lubricant flows through the lubrication fitting into the cavity, radially outwardly from the cavity through each of the lubricant passageways, around the ends of the trunnions, and radially inwardly into the region of the bearings. A seal and dust guard assembly may be provided about the open end of each of the bearing cups to retain the lubricant in the region of the bearings and to prevent the entry of dirt, water, and other contaminants therein.
In the past, conventional universal joint assemblies have been designed such that the above-described lubrication process can be performed at relatively frequent intervals. To accomplish this, the seal and dust guard assemblies have been structured in such a manner as to allow excess lubricant to flow therethrough from the region of the bearings to the exterior of the bearing cup. Consequently, the above-described lubrication process can be performed as often as desired without causing any damage to the seal and dust guard assemblies. More recently, however, universal joint assemblies have been structured such that the above-described lubrication process should be performed only at relatively long time intervals, if at all. In these more recent universal joint assemblies, the seal and dust guard assemblies are not designed to allow lubricant to flow therethrough in either direction. However, it has been found that in some instances, service personnel occasionally have difficulty determining whether a particular universal joint assembly being serviced is of the older type (that does requires relatively frequent lubrication) or of the newer type (that does not require relatively frequent lubrication). As a result, such service personnel occasionally attempt to inject lubricant into a newer type of universal joint assembly, which can possibly yield undesirable results. Thus, it would be desirable to provide a simple and inexpensive mechanism for clearly identifying the newer types of universal joint assemblies and for positively deterring the injection of lubricant therein.